Preheat the oven to 220°C and line a baking sheet with parchment marked with four 10cm circles.
Sift the flour onto parchment and heat milk, salt, sugar, butter, and 80ml water in a pan.
Add flour to the boiling liquid and beat vigorously until a dough forms, then cook for 5 minutes.
Cool slightly, beat in eggs gradually until glossy, and pipe four rings onto the parchment circles.
Brush the rings with egg wash and sprinkle with flaked almonds.
Bake at 220°C for 15 minutes, then at 180°C for 10 minutes, slice horizontally, and dry in oven for 4 minutes.
Melt caster sugar into caramel, coat hazelnuts, cool on a silicone mat, and process into fine dust.
Whip double cream with vanilla seeds until soft peaks form and place in a star-nozzle piping bag.
Layer praline and cream inside the rings, replace the lids, dust with icing sugar, and serve.